The present invention relates to a heat blowing structure for a thermal print head of a color video printer, and more particularly to heat blowing equipment for mounting a heat blowing fan interlocked with the up and down operation of a thermal print head, thereby improving heat blowing effect during printing.
With reference to FIG. 1 which is a whole sectional view of a conventional color video printer, the construction of conventional equipment is described.
A conventional thermal print head 4 is mounted on the end of a holder 5, which is connected rotatably by a hinge 6. And, a radiating plate 3 is mounted on the upper side of the thermal print head 4, as shown in FIG. 2. A platen roller 11 for printing by pressing dye film 8 and printing paper 15 are provided in the lower portion of the thermal print head 4, and a grip roller 9 and a pinch roller 10 for feeding the printing paper 15 are mounted to one side of the platen roller 11.
Dye film 8 is provided on the inside of a dye film cassette 7, in such a manner that the dye film 8 is rolled around a supply reel 7b and a take-up reel 7a. A heat blowing fan 1 is fixed with a cover 14 by fixing means such as a screw 2, above the thermal print head 4.
In the arrangement described above, if printing paper 15 is supplied by the grip roller 9 and the pinch roller 10 in response to a print signal, the holder 5 where the thermal print head 4 and the radiating plate 3 are mounted is moved to a lower position around the hinge 6, and presses the dye film and the printing paper on the platen roller 11 as shown in FIG. 1. Here, printing paper 15 is fed by the rotation of grip roller 9, thereby being printed. The holder 5 comprising the radiating plate 3 and the thermal print head 4 moves up and down around the hinge 6 by conventional lever equipment, according to the rotation of a cam 13.
When the thermal print head 4 generates heat to print thermally on the printing paper 15, the heat generated in the head 4 is cooled through the radiating plate 3. That is, the fan 1 fixed on the cover 14 cools the radiating plate 3 by circulating external air. In such a conventional cooling structure, since the cooling fan 1 is fixed with the cover 14, it is impossible for air to be sent to the radiating plate at both of two positions, i.e., at the upper position before/after printing and the lower position during printing. That is, since the thermal print head 4 moves to the lower portion during printing, wind supplied from the fan 1 is exactly transferred to the radiating plate 3. However, in this case, when the printing is completed or is in a continuous printing mode, since the thermal print head 4 moves to the upper position, i.e., into a standby position, the radiating plate 3 becomes relatively far removed from the direction of the wind supplied from the fan 1, so that it is difficult to be well ventilated. Particularly during continuous printing, the temperature of the thermal print head should be constant and like its temperature upon first starting. However, if the print head is not reliably cooled in the standby state of the thermal print head, i.e., in the upper position before being in contact with the platen roller, there is a problem of deterioration in printing quality because of differences in color tone and color strength, compared with the print picture of a normal state.